02-19-2014, 10:56 AM
Ron
Also, those 330 Ohm resistors, the R36/R38.....those gotta be large - they constantly dissipate at ;east 1.5W so they are probably high wattage, like 4-5W types. See if one of them has drifted. There is no DC feedback in this amp (not that I see) and there is nothing else to ensure the 45V voltage divides equally (BTW not sure where they came up with those 46V and 46.2V numbers if the power is 45V with no active conversion) into 22.5V except those resistors (there is the inter-stage transformer concept for you) so you dissipate some extra.
So, it is either the resistors or the cap leaking. The leaking cap is readily eliminated by unplugging the load (BTW make sure your load is 0 Ohm when there is no speakers - like your phone jack is shorted or has something in it...conducting....a dead roach....). And it has to be some leakage too to overpower 75mA of current.
If it is still the case, measure the resistors then.
PS> just an idea - for seeing if a regular good cap makes a difference you could use one of them tube radio caps - just use 20 to 100 uF cap. You will also get sound with the base attenuated.
Also, those 330 Ohm resistors, the R36/R38.....those gotta be large - they constantly dissipate at ;east 1.5W so they are probably high wattage, like 4-5W types. See if one of them has drifted. There is no DC feedback in this amp (not that I see) and there is nothing else to ensure the 45V voltage divides equally (BTW not sure where they came up with those 46V and 46.2V numbers if the power is 45V with no active conversion) into 22.5V except those resistors (there is the inter-stage transformer concept for you) so you dissipate some extra.
So, it is either the resistors or the cap leaking. The leaking cap is readily eliminated by unplugging the load (BTW make sure your load is 0 Ohm when there is no speakers - like your phone jack is shorted or has something in it...conducting....a dead roach....). And it has to be some leakage too to overpower 75mA of current.
If it is still the case, measure the resistors then.
PS> just an idea - for seeing if a regular good cap makes a difference you could use one of them tube radio caps - just use 20 to 100 uF cap. You will also get sound with the base attenuated.
